It's time to put this argument to bed. In terms of BIG matches they go like this(from biggest to least):
1. World Cup Final
2. Champions League Final
3. World Cup knockouts
4. Champions League knockouts
5. Euros final
6. Clasico(for Barcelona or Real Madrid players) or big team match in another league like Man U vs Arsenal or something.
7. Euros knockouts
8. Copa America Final
9. Copa America knockouts
10. Champions League group stages
11. Top 5 European league matches against non-big teams
12. World cup qualifying matches
13. Cup matches(copa del rey, FA Cup, DFB pokal, etc.)
14. Friendlies
I think that we can more or less agree on this ranking with maybe a few adjustments depending on your personal opinion.
Neymar has played one Classico, 6 CL group matches, one Copa America knockout match(not 100% sure on this), and less than half a season in La Liga. He has played in a Copa Libertadores final which is probably top 10, as well.
Gotze has played in several derbies, several matches against Bayern for Dortmund and one for Bayern against Dortmund, I believe about 10-15 CL group stage matches, I think 5 CL knockout matches, and is in his 3rd season playing consistent games in a top European league.
Let me reiterate that I don't think one is better than the other but it is QUITE CLEAR that Gotze has played in more big matches. There is no debating that.
Confederations final is probably somewhere around the same level as a CL group stage match or maybe a little bit higher but not by much in terms of a big match.